W. B. D WIGHT. 147 



much interest in geological science that it is one of the 

 most prominent features in this local exploration, and 

 deserves the most careful study. Though it would give 

 me much pleasure, if the facts observed should enable 

 me to announce the certainty of synchronism in the two 

 fauna as established at Rochdale, yet, as I have already 

 intimated, there has not yet been evident that true inter- 

 mingling of fossils which would fairly establish this con- 

 clusion Further observations may modify this view. 



Another conclusion desirable from this proximity of 

 the two sets of fossils, is that it shows that no inter- 

 mediate deposit could have occurred in this vicinity ; 

 consequently, if the lower limestone is the calciferous, 

 there must have been quite a suspension of deposits 

 here, (presumably by temporary elevation into dry land,) 

 while the intermediate strata found elsewhere, were be- 

 ing deposited. The facts, however, give additional prob- 

 ability to the theory that the lower limestone is more 

 closely related to the Trenton limestone than the calcifer- 

 ous would be. 



This brings me to the last point which I will mention 

 in connection with the stratigraphy, which I will put in 

 the form of a question. Do the investigations of the 

 last two or three years increase or diminish the proba- 

 bility of the view taken in the earlier stages of the work, 

 that the lower limestone belongs to the calciferous 

 group \ 



The first assignment to the calciferous group was 

 made by myself, in consequence of finding fossils corre- 

 sponding better to the ordinary calciferous fossils of the 

 United States than to any others. It is true that the 

 list of such fossils in our country is exceedingly meagre, 

 very poorly understood, and very vaguely described. 

 But those at that time found at Rochdale were not of a 

 nature to raise much doubt, or, at least, to give much 



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